Existing are some soft touch drain valves, for example a double chain type double flow drain valve in the Chinese patent database with announcement number CN203684356U, which is provided to respectively adjust the high and low volume of the flushing water by two barrels vertically arranged, the upper barrel is a float, the bottom barrel is a float when the drain valve doesn't flush water and when the drain valve drains high volume of water, and it refills water when the drain valve drains low volume of water, this kind of technical proposal has unstable drainage volume, and it needs to close two sealing pad when in high and low drainage volume, it is easy to leak, and it is of bad application and complicated to operate.